This invention relates to testing elastic barriers for permeability to microscopic particles. In particular, this invention relates to testing such barriers used in the prevention of disease transmission.
Barrier membranes made of elastic material have been used to prevent the transmission of microorganisms and the diseases they cause. Well known examples of such use are surgical gloves and condoms, both typically made of latex rubber. Originally developed as a means of preventing pregnancy, condoms have become increasingly important in preventing the spread of sexually transmitted diseases, especially the recently discovered acquired immune deficiency syndrome, commonly known as AIDS.
In this regard, typical membranes having a pore size between 0.1 and 0.4.mu. have been shown effective in blocking microorganisms such as bacteria and fungi. However, the efficacy of such barriers is questionable with respect to virus-caused diseases, such as AIDS, which often have particle diameters less than 0.1.mu.. Accordingly, the importance of membrane-permeability testing has become increasingly important with the awareness of diseases caused by viruses.
Few studies have been conducted to test barrier membrane permeability to viruses. In one such study, condom permeability was tested by merely immersing a condom containing a liquid suspension of a virus in a liquid growth medium for the virus, and assessing viral appearance in the growth medium (see Abstracts of the III International Conference on AIDS, Washington, D.C., 1987).
However, in actual use, elastic barrier membranes are frequently subjected to stretching and abrasion, sometimes over extended periods of time. For example, surgical gloves may be subjected to different stretching parameters depending on the size of the user's fingers, the frequency and force of finger movement required, and the abrasiveness of the material encountered during a particular session, the duration of which often varies depending upon surgical skill. Such stresses may adversely affect the original pore size of the barrier, i.e., a barrier originally impermeable to a small particle may dramatically lose its impermeability properties both during and after stretching.